Lubricant compositions

ABSTRACT

THE INVENTION RELATES TO ADDITIVES FOR LUBRICANTS CONTAINING METAL SALTS, AND ALSO TO THE LUBRICATING COMPOSITIONS OBTAINED WITH THE AID OF THESE ADDIVTIVES. THE INVENTION ALSO HAS AS ITS OBJECT A PROCESS FOR PRODUCING SUCH ADDITIVES. THE INVENTION MAKES IT POSSIBLE TO OBTAIN STABLE MIXTURES OF MINERAL OILS OR OF SYNTHETIC LUBRICANTS AND ALKALI OR ALKALINE EARTH METAL SALTS AND ALSO LEAD SALTS HAVING A HIGH METAL CONTENT. THE INVENTION RELATES PARTICULARLY TO ADDITIVES FOR STABLE LUBRICATING COMPOSITIONS IN WHICH THE METAL CONTENT, PARTICULARLY AN ALKALINE EARTH METAL SUCH AS CALCIUM, IS 5-6% THAT IS TO SAY BEFORE DILUTION IN A LUBRICATING OIL. THE INVENTION ALSO RELATES TO CONCENTRATED, STABLE, HOMOGENEOUS ADDITIVES HAVING A HIGH LEAD CONTENT, WHICH MAY FOR EXAMPLE AMOUNT TO 30-40% BY WEIGHT. THE LUBRICANT ADDITIVE ACCORDING TO THE INVENTION COMPRISES A MIXTURE OF SALTS FORMED BY REACTING AT LEAST ONE BRANCHED CHAIN CARBOXYLIC ACID CONTAINING 5-20 CARBON ATOMS WITH (A) A BASIC METALLIC OMPOUND SELECTED FROM THE OXIDES AND HYDROXIDES OF ALKALI METALS, ALKALINE EARTH METALS AND LEAD AND, (B) AT LEAST ONE ALKANOLAMINE.

United States Patent Office 3,554,909 Patented Jan. 12, 1971 US. Cl. 252.34.7 Claims ABSTRACT OF THE DISCLOSURE The invention relates to additives for lubricants containing metal salts, and also to the lubricating compositions obtained with the aid of these additives. The invention also has as its object a process for producing such additives. The invention makes it possible to obtain stable mixtures of mineral oils or of synthetic lubricants and alkali or alkaline earth metal salts and also lead salts having a high metal content. The invention relates particularly to additives for stable lubricating compositions in which the metal content, particularly an alkaline earth metal such as calcium, is 56% that is to say before dilution in a lubricating oil. The invention also relates to concentrated, stable, homogeneous additives having a high lead content, which may for example amount to 30-40% by weight.

The lubricant additive according to the invention comprises a mixture of salts formed by reacting at least one branched chain carboxylic acid containing 5-20 carbon atoms with (a) a basic metallic compound selected from the oxides and hydroxides of alkali metals, alkaline earth metals and lead and,

(b) at least one alkanolamine.

The invention relates to additives for lubricants containing metal salts, and also to the lubricating compositions obtained with the aid of these additives. The invention also has as its object a process for producing such additives.

In particular, the invention makes it possible to obtain stable mixtures of mineral oils or of synthetic lubricants and alkali or alkaline earth metal salts and also lead salts having a high metal content.

It is known that it is necessary for a substantial amount of metal salts, particularly alkaline earth metal salts, to be introduced into certain engine lubricants in order to neutralise the effect of the sulphur contained either in the fuel burned by the engines or in the lubricant itself, or else in both simultaneously, the latter case being the most frequent. Additives based on calcium for example are generally dispersed in the oil or peptised but the amount of calcium which can be introduced in this way is limited, and the compositions obtained are not very stable.

The invention relates particularly to additives for stable lubricating compositions in which the metal content, particularly an alkaline earth metal such as calcium, is 56% that is to to say before dilution in a lubricating oil. The invention also relates to concentrated, stable, homogeneous additives having a high lead content, which may for example amount to 30-40% by weight.

The additive according to the invention contains essentially at least one salt of a metal selected from the alkali metals, alkaline earth metals, and lead, alkanolamines, and C -C branched carboxylic acids, natural or Thus, a salt of this type may be used within a mineral oil, such as a naphthenic oil, in the form of a concentrate and the concentrated additive may then be diluted by simple mixing in an oil in order to form the desired lllbllcating composition. In certain cases the concentrate may be used as it is to serve as a fluid or viscous lubricant.

In particular, the invention makes it possible to obtain in an advantageous manner lubricating compositions based on petroleum fractions and calcium salts and/ or lead salts.

Compositions based on barium salts can be prepared under the same conditions and the process, which is useful in the particular case of the introduction of alkaline earth metal salts into engine lubricants, can also be applied to other metal salts, particularly to salts of alkali metals such as sodium and potassium. The lead containing lubricating compositions in particular have excellent anti-wear properties under heavy loads and at the same time possess anti-rust properties.

In order to obtain the additives proposed by the invention use is preferably made of aliphatic monocarboxylic acids having branched hydrocarbon chains, which are obtained for example from aldehydes produced by the method known as oxo synthesis, in which the number of carbon atoms is between 7 and 14. These acids will be referred to hereinafter by the simplified expression 0x0 acids and enable perfectly homogeneous and stable lubricating compositions to be obtained.

It is particularly advantageous to use oxo acids containing from 8 to 10 carbon atoms, either alone or in mixtures.

With the 0x0 acids the molecular ratio of the amino alcohol to the metallic base composition (calcium oxide or lead oxide) is generally between 0.1 and 0.3. It may be higher than 0.3, but this does not give any practical advantage.

In order to form the new lead salts proposed by the invention, it is particularly advantageous to use the 0x0 acid containing 10 carbon atoms and triisopropanolamine, which make it possible to prepare concentrates having a high lead content in parafiinic mineral oils, naphthenic mineral oils, and also bases for synthetic lubricants, such as carboxylic acid esters or polyoxyalkylene glycol ethers.

The synthetic, branched aliphatic chain carboxylic acids used may also be ethylhexanoic acid or the acids obtained by the reaction of branched olefins with carbon monoxide and water, particularly the acids marketed by the Shell International Petroleum Company under the trademark Versatic.

Natural carboxylic acids, used alone, do not generally lead to limpid, i.e. clear compositions, and do not permit the formation of concentrates in mineral oil which are as homogeneous and as stable as in the case of the synthetic acids. An exception to this rule is however mixtures of fatty acids derived from tall oil, which may lead to satisfactory results, and the ethylenic acids.

The use of mixtures of natural carboxylic acids containing from 7 to 18 carbon atoms and of synthetic acids, such as oxo acids containing from 7 to 14 carbon atoms and preferably 8 to 10 carbons, or Versatic, acids, nevertheless remains within the scope of the invention because it makes it possible to obtain satisfactory additives and compositions.

In the latter case, and particularly when use is made of calcium as the metallic constituent, the synthetic acid/natural acid molecular ratio is greater than 0.1:1 and the amino alcohol/calcium ratio is equal to or greater than 0.3:1 being generally between 0.30.5:1; the natural acids preferably used are natural acids containing 8 to 12 carbon atoms or oleic acid; the synthetic acids preferably used are the 0x0 acids containing from 7 to 14 carbon atoms, the acids obtained by Koch synthesis which contain from 9 to 11 carbon atoms or ethylhexanoic acid.

When lead is used as metallic constituent and use is made of mixtures of straight chain carboxylic acids containing from 7 to 18 carbon atoms and of synthetic branched chain carboxylic acids preferably containing from 8 to 10 carbon atoms, it is advantageous to have a major proportion of synthetic carboxylic acid in the mixture, which is most advantageously the x0 acid containing 10 carbon atoms, and previously to mix the lead oxide and the alkanolamine salt, for example the triisopropanolamine salt of 0x0 acid containing 10 carbon atoms.

Suitable alkanolamines or amino alcohols are the ethanolamines, propanolamines, and butanolamines, a preferred material being triisopropanolamine alone or in a mixture with mono-, and di-, isopropanolamines in which there is a major proportion of triisopropanolamine.

The use of ethanolamines, preferably triethanolamine, or of mixtures of mono-, di-, and triisopropanolamines is advantageous for the preparation of the lead salts in the naphthenic bases.

Triisopropanolamine is also preferred in order to obtain stable, limpid compositions having a high lead content in mineral and synthetic oils, with a molecular ratio of amino alcohol/lead oxide of about 0.3.

The ethanolamines and monoand diisopropanolamines which can be used alone are less effective than triisopropanolamine and do not allow the formation of compositions having a high content of alkali or alkaline earth metal, such as calcium. They are also less limpid and stable than compositions containing triisopropanolamine for the same molar or Weight concentrations.

A process for obtaining an additive according to the invention comprises neutralising, by at least one carboxylic acid as hereinbefore defined above, a metallic compound selected from alkali metal, alkaline metal, and lead oxides and hydroxides, intimately mixed with an alkanolamine.

As a variant it is possible to mix the metallic oxide or hydroxide with the salt of an amino alcohol and a carboxylic acid, as hereinbefore defined and then to neutralise this previously formed mixture with a carboxylic acid or a mixture of carboxylic acids as hereinbefore defined.

The reaction may be carried out in a mineral oil and it is also possible to add the mineral oil (in a suitable amount for obtaining a concentrate) when the mixture of alkali or alkaline earth oxide or hydroxide and amino alcohol is completely neutralised.

With calcium oxide, for example, concentrates can be obtained which contain from to 6% of calcium in the naphthenic oil, these concentrates being transparent and stable and being mixed by simple agitation with the naphthenic oil.

The process according to the invention also makes it possible to obtain additives and lubricating compositions containing up to 40% of lead or more, which are in the form of viscous, stable, limpid homogeneous liquids.

A process for the preparation of lead salts for example, in which lead oxide is reacted alone, without a solvent, with the previously defined organic acids leads to additives having limited solubility in mineral oils which do not give stable, homogeneous concentrates by simple mixing with the oils. In addition the process requires higher temperatures and much longer reaction times than those required in the process of the present invention.

The process of preparation of the additives according to the invention obviates the necessity of adding light solvents which tend to lower the flash point of the lubricating compositions into which they are introduced and which also tend to reduce their anti-wear properties.

When using a diluent, the metallic compound, for example finely ground calcium oxide, is formed into a paste with an amino alcohol or a mixture of amino alcohols until a homogeneous cream is formed, whereupon the amount of oil corresponding to the desired calcium content is added, for example 5 to 6% by weight in the concentrate, after which, while maintaining the temperature at about 6070 C. by means of a thermostatically controlled circulation, the amount of acid necessary for neutralisation of all the alkalinity is progressively introduced. The reaction is terminated, after introduction of all the acid, by heating to 90 C. for about one hour with agitation, and the concentrated mixture obtained may be diluted with mineral oil at the rate required for use.

When lead is used as metallic constituent, mixtures of neutral or basic lead salts of organic acids and of amino alcohol salts of organic acids may be prepared.

The neutral salts are obtained when the amount of organic acid in gramme equivalents is equal to the total of the amounts of amino alcohol and lead in gramme equivalents.

For the basic salts, the total of the amounts of amino alcohol and lead in gramme equivalents is greater than the amount of organic acid in gramme equivalents.

In the latter case, the presence of amino alcohol salts of carboxylic acids facilitates the preparation of the basic lead salts, but has a less marked efiect on the solubilisation of the additives in the oils than in the case of the neutral salts.

In this respect it is possible either to add the carboxylic acid to the intimate mixture of lead oxide and amino alcohol, or to add the acid necessary for the formation of the neutral or basic lead salts to the mixture of lead oxide and amino alcohol salt of the carboxylic acid.

The reaction may also be carried out in a mineral oil in order to obtain a concentrate directly or a lubricating composition having a high lead content.

A variant in the preparation of a concentrate in a natural or synthetic oil comprises making a mixture, in the oil of a lead salt prepared in the conventional manner by reaction of lead oxide alone with the organic acid, with the amino alcohol salt of the carboxylic acid.

This variant demonstrates the solubilising and dispersing properties of the amino alcohol salts of carboxylic acids and in particular of the triisopropanolamine salt of the oxo acid containing 10 carbon atoms, which is the most effective when lead is used as metallic constituent.

The final composition may, if required be filtered in order to eliminate the impurities contained in the starting metallic constituent and may also be dried to eliminate the water formed in the course of the reaction.

The proportion of amino alcohol salts in the final mixture necessary for obtaining a stable lubricating composition depends, for a particular metal salt on the length and the structure of the hydrocarbon chain of the acid used, the structure of the amino alcohol, and the nature of the petroleum lubricant. It is therefore useful in practice to carry out preliminary tests in order to determine in each case the amount of amino alcohol necessary to obtain a stable lubricating composition.

The examples below illustrate the invention and emphasise the advantages offered by the process and by the compositions. The amounts of reagents are expressed in moles, while the purity of the different reagents used, which are designated in the examples by the following references, is defined by their mean molecular weight:

Mixed isopropanolamine (mixed iso): commercial mixture of mono-, di-, and triisopropanolamines of the mean molecular weight-l22.

Triisopropanolamine (tri iso): mean molecular weight C 0x0: 0x0 acid containing 8 carbon atoms, mean molecular weightl55.

C 0x0: 0x0 acid containing 10 carbon atoms, mean molecular weight-l73.

Versatic acid: synthetic acid of mean molecular weightl84.

Ethylhexanoic acid: synthetic acid of molecular weight- The lead oxide used was a litharge of which the PhD content is greater than 99% by weight.

The lime used contained only 95% of calcium oxide and the amino alcohols had a purity of 96-98%.

EXAMPLE 1 A mixer of a capacity of 5 litres was used, equipped with a double envelope permitting thermostatically controlled circulation.

5 mols of finely ground calcium oxide were introduced into the mixer, followed by 1.5 mol of triisopropanolaminefthe temperature of the fluid circulating in the double envelope was adjusted to 65-70 C. and agitation was started. When the mixture had the appearance of a homogeneous paste, 1.5 kg. of naphthenic oil of a viscosity of 315 centistokes at 38 C. was added. When the calcium oxide and the amino alcohol were suitably dispersed in the oil, 11.5 moles of a C oxo acid molecular weight 173 (the amount necessary to neutralise all the amino alcohol in the base), was progressively introduced over a period of about 45 minutes. After 50% of the total amount of acid had been introduced within 20 minutes, the temperature in the mixture rose to between 75-80 C., and the rate of addition of the acid was reduced so as to introduce the remainder over a period of 30-35 minutes.

The temperature was then adjusted to 75-80 C., while maintaining agitation for 1 hour before finally allowing the mixture to stand at 80-85 C. without agitation in order to permit degassing.

Filtration may be effected on the mixture in order to eliminate the non-neutralisable impurities contained in the lime.

A perfectly limpid composition was obtained which.

contained approximately 5% by weight of calcium in the naphthenic oil. This concentrate is diluted in the naphthenic oil by simple agitation, is miscible with aromatic hydrocarbons such as benzene, toluene, and xylene, and with halogenated solvents, and with parafiinic oils forms homogeneous mixtures which are stable when stored. This concentrate, when mixed with synthetic lubricants of the polyoxyalkylene glycol ether type, also provides transparent, stable compositions.

A lubricating composition in which the additive prepared as described above had been incorporated to give a level of 1.5% by weight of calcium possessed lubricating properties which were markedly superior to the base oil. Its mean Hertz load, determined on a 4-ball machine in accordance with method 6503 of FS Standards Series No. 791, attained 50 kg. as against 31 kg. for the base oil.

The corrosion resistance of ferrous metals was also improved on exposure of the metals to the action of the additive described above.

EXAMPLE 2 The operation was carried out under identical conditions to those in Example 1, but without introducing amino alcohol. When the amount of C oxo acid required to neutralise the calcium oxide had been introduced, a heterogeneous mixture was obtained which contained calcium salt agglomerates and despite continued kneading at temperatures lower or higher than C., homogenisation of the mixture was not possible. The subsequent addition of the salt of the 0x0 acid containing 10 carbon atoms and of triisopropanolamine or other amino alcohol did not assist the dispersion of the calcium salt.

EXAMPLE 3 The procedure of Example 1 was followed save that 5 mols of calcium oxide were formed into a paste with 1.5 mol of the salt of the C oxo acid and triisopropanolamine, and then 1.5 kg. of naphthenic oil were added, followed by a further 10 mols of the C oxo acid. At the end of the operation a composition was obtained which was identical to that obtained in Example 1.

Table I below summarises the results of the tests carried out under the same conditions as those in Example 1, but with diiferent reagents. The reagents were introduced into the kneader in the order indicated. All the neutralisation reactions were effected in a naphthenic oil of the viscosity 315 centistokes at 38 C. The oil was introduced into the mixer after the calcium oxide and the amino alcohol, in an amount sufiicient to obtain at the end of the operation a composition containing 5% of calcium.

In the table are indicated the appearance of the concentrate containing 5% calcium after filtration, the appearance of the dilute composition in naphthenic oil containing 1.5% of calcium, stability in storage at ordinary temperature of the two compositions, and also thermal stability at C. for 24 hours for the formula containing 1.5% of calcium.

For convenience in writing, the various reagents used are designated in the tables by the following references:

Mono iso: monoisopropanolamine Di iso: diisopropanolamine Tri iso: triisopropanolamine Mixed iso: commercial mixture of mono-, di-, and triisopropanolamines (mean molecular lw'eightl22).

C oxo: 0x0 acid containing 8 carbon atoms (mean molecular weightlSS C oxo: oxo acid containing 9 carbon atoms (mean molecular weight161) C oxo: oxo acid containing 10 carbon atoms (mean molecular weight173) C oxo: oxo acid containing 13 carbon atoms (mean molecular weight2 1 1 Versatic acid: synthetic acid of mean molecular Weight-184 Tall oil acid: mixture of acids derived from tall oil, mean molecular weight-264 C N: pure caprylic acid C N: pure pelargonic acid C N: pure capric acid.

TABLE I.COMPOSITIONS CONTAINING CALCIUM SALTS Characteristics of composition .con- Characteristics of composition con- Reagents taining 5% of calcium taining 1.5% of calcium Example 4:

5 .33 fg a Transparent viscous fluid stable in Stable transparent fiuid stable in 00 1 I storage. storage, stable at 100 0. Example 5:

CaO, 5 mols Tri iso, 1.5 mols ..do Transparent fluid stable in storage, Versatic acid, 11.5 mols stable at 100 0. Example 6:

CaO, 5 mols riiso,15.5m1ols. Very viscous opaque paste Opaque dispersion, slight deposition. v mo s Example 7:

Ca 5 mols 3f: 5 g gg Turbid viscous paste, stable in storage. Slightly turbid fluid, stable in storage, CNy 6 nlolsuui stable at 100 C.

C N, 6.25 mols Slightly turbid viscous fluid, stablein Very slightly turbid fluid, stable in s orage.

storage, stable at 100 C.

Characteristics of composition containing 5% of calcium Reagents Example CaO, mols Cm 0x0, 8 mols Example 10:

Tri iso, 1.5 mols.

Ca 0x0, 11.5 mols Example 11:

CaO, 5 mols c.

cuo'smols Translucent viscous fluid, stable in storage.

CsN,11.5 mols Example 12:

CaO, 5 mols 'lri iso, 1.5 mols.

Tall oil acid, 11.5

. The composition containing 4% of calcium by Weight is a transparent TABLE I.-Corrtlnued Characteristics of composition containing of calcium 'lransparent fluid, stable in storage,

stable at 100 C.

Slightly cloudy fluid, stable in storage,

stable at 100 0.

Very viscous fluid, unstable.

Limpid fluid, stable in storage, stable at 100 C.

viscous fiuid, stable in storage.

Example 13:

g 1 1 Perfectly limpid viscous fluid, stable Perlectlylimpid fluid, stablein storage, mo in storage. stable at 100 C.

13, 0x0, 11 mols Example 14: I

CaO, 5 mols Transparent viscous fluid, stable in Slightly turbid fluid at C., lllllpld Mono iso, 2.2 mols. storage. at 100 C., stable at 100 C., stable in C10 0x0, 12.2 mols storage.

Example 15: 1

G10, 5 m0 s 4 Did-s0y 2 m 01S }Opaque paste, stable in storage lllld, stable in storage, 010 0x0, 12 mols Example 16: l

CaO,5mos 7 Triethanolamine 2 mols er; viscous paste, stable in storage... 8111551621?) turbid VISCOUS fluid, stable at Cm 0x0, 12 mols The application of the invention to the introduction of salts of metals other than calcium, for example barium, sodium, and potassium salts is illustrated by Examples 17-20. The tests which led to the preparation of the compositions described in these examples were carried out either by using naphthenic oil having a viscosity of 315 centistokes at 38 C. as diluent, or by neutralising the metallic oxide or hydroxide mixed with the amino alcohol wighout diluent and adding the naphthenic oil after complete neutralisation. Preparation of the metal salts in the absence of amino alcohol did not enable suitable compositions to be obtained in any case. These examples show, in particular in the case of the alkali metals, the influence of the relative proportions of metal oxide or hydroxide and amino alcohol.

EXAMPLE 17 Neutralisation of a mixture of 1 mol of barium oxide and 0.3 mol of triisopropanolamine by a C oxo acid in the presence of a naphthenic oil having a viscosity of 315 centistokes at 38 C., as diluent, allowed the formation of an opaque, viscous composition which was stable during storage and contained by weight of the mixture of barium and triisopropanolaminc salts.

A composition containing 20% by weight of the mix- I ture of the above salts was a transparent fluid which was stable during storage.

EXAMPLE 18 The procedure of Example 17 was followed replacing the C oxo acid by a C oxo acid.

Compositions containing 50% and 20% by weight of the mixture of salts of the 0x0 acid in the naphthenic oil had the same appearance as the compositions containing the salts of the C9 oxo acid.

EXAMPLE 19 The sodium salt of a C oxo acid which is solid at ordinary temperature, was not dissolved or suitably dispersed in oils.

By neutralising the mixture of 1 mol of ground soda and 0.3 mol of triisopropanolamine by 1.3 mol of a C oxo acid a perfectly limpid soap of low viscosity was obtained which together with light or viscous naphthenic bases and paratfinic bases formed stable transparent compositions.

EXAMPLE 20 The mixture of salts obtained by neutralising 1 mol of ground potash, formed into a paste with 0.3 mol of triisopropanolamine, by means of a C oxo acid is a perfectly limpid liquid soap, but the composition containing 50% by weight of this soap and 50% by weight of naphthenic oil of a viscosity of 315 centistokes at 38 C. was not stable and formed a sediment at ordinary temperature.

By increasing the amount of triisopropanolamine to 0.4 mol of triisopropanolamine to 1 mol of potash for example, the soap obtained, when mixed with its own weight of naphthenic oil, formed a stable transparent composition.

Examples 21-26 illustrate the preparation of lead-containing compositions.

EXAMPLE 21 A 5 litre mixing vessel was used fitted with a double jacket permitting thermostatically controlled circulation and also with a condenser for the collection of the water of reaction.

The temperature of the heating fluid was fixed at about -80 C. and 1.5 mol of triisopropanolamine was introduced into the mixer and after the amine had melted, 5 mols of powdered lead oxide were introduced gradually so as to obtain a homogeneous paste. When the litharge was suitably dispersed in the amino alcohol, 11.5 mols of a C oxo acid were introduced.

The temperature was then adjusted to approximately C. and this temperature was maintained for a period of three hours until a practically limpid reaction product was obtained.

The reaction was then completed by heating for a period of 30 minutes to 1 hour at 115 C.

When a litharge was used which contained a minimum of 99% by weight of PbO, a perfectly limpid viscous product was obtained which contained 31.331.0% by Weight of lead, depending on whether all or only part of the water of reaction had been eliminated.

The elimination of water may be assisted either by bubbling-in nitrogen in the course of the reaction, or by a final treatment with a dehydrating agent, for example anhydrous calcium sulphate, followed by filtration.

This additive formed stable, limpid compositions containing from 0 to 30% of lead with the mineral or synthetic lubricating bases of the following type:

Mineral oil SAE 80 of a parafiinic character;

Mineral oil SAE 90 of a paraffinic character;

Naphthenic mineral oil of a viscosity of 315 centistokes at 38 C.;

Polyoxypropylene glycol ethers of viscosities of 20 and cs. at 38 C.;

Esters of monobasic or dibasic carboxylic acids and of monoor polyalcohols.

EXAMPLE 22 The procedure of Example 21 was followed save that mols of litharge were introduced into the salt obtained by neutralising 1.5 mol of triisopropanolamine with 1.5 mol of C oxo avid and the remaining 10 mols of acid were poured in when the litharge had been suitably formed into a paste.

A product was obtained which had the same appearance and the same characteristics as the additive of Example 21, but the order in which the reagents were introduced made it possible to avoid the highly viscous state which characterises the triisopropanolamine-litharge mixture.

EXAMPLE 23 1470 grams of mineral oil SAE 90 of paraflinic character were introduced into the mixer, followed by 230 grams (1.2 mol) of triisopropanolamine; the mixture was heated to about 80 C. in order to melt the amine and disperse it in the mineral base and 892 grams (4 mols) of litharge were then added. After waiting until the mixture was homogeneous, 1592 grams (9.2 mols) of C oxo acid were poured in. The ingredients were allowed to react at 100105 C. until the litharge had completely disappeared, that is to say for 2% hours to 3 hours. The reaction was then completed by heating at 110-115 C. in order to eliminate the maximum quantity of water.

A concentrate of lead salt of C oxo acid was obtained which contained 20% of lead and was in the form of a transparent liquid of a viscosity of 500 cs. at 50 C.

EXAMPLE 24 The process was carried out under identical conditions to those in Example 23, but without introducing triisopropanolamine and utilising 4 mols of litharge and 8 mols of C oxo acid. The disappearance of the litharge was achieved after a much longer period of heating at 100-105 C. than in Example 23, namely 4 hours instead of from 2% to 3 hours. After stopping the agitation, a heterogeneous mixture was obtained which separated into two layers. The major part of the lead salt was contained in the lower layer.

The addition of an additional quantity of SAE 90 oil in order to adjust the lead content in the reactional medium to 20% and then to followed by prolonged agitation at a temperature of about 70-8 0 C. did not produce stable, homogeneous concentrates.

On the other hand, the addition of 1.2 mol of the Example No.

Reagents (mols) 10 salt of the C oxo acid and triisopropanolamine, fol lowed by agitation for about 15 minutes, to the mixture obtained under the same conditions by reaction of 4 mols of litharge and 8 mols of C oxo acid, produced a concentrate containing 20% of lead and in every way identical to the concentrate of Example 23.

EXAMPLE 25 The process was carried out under identical conditions to those of Example 22, but replacing the triisopropanolamine by mixed isopropanolamine. A highly viscous, limpid additive was obtained which contained 32% of lead and was miscible with naphthenic oil of a viscosity of 315 centistokes at 38 C., but the solubility of which in SAE and SAE paraffinic oils was poorer than that of the additive of Example 21.

EXAMPLE 26 The process was carried out under conditions identical with those of Example 22, but replacing the triisopropanolamine by tn'ethanolamine. The additive obtained was miscible with naphthenic oil of a viscosity of 315 centistokes at 38 C. and the concentrates in paraflinic oils were stable but slightly turbid. Table II below summarises the results obtained with other synthetic acids than C oxo acid.

For the additives prepared from litharge and amino alcohols the procedure described in Example 22 was followed.

The lead salts without amino alcohol salts were obtained by gradually introducing litharge into the acid, the reaction medium being brought to 115 C. and heating and agitation being maintained until the litharge completely disappeared.

The miscibility of the additives in mineral oils was examined. In the table there are noted the results obtained with the SAE 90 parafiinic mineral oil, a solvent which has been found far less effective than the naphthenic oil mentioned in the preceding examples.

The term miscible characterises additives which formed limpid and stable mixtures in any proportions with the SAE 90 oil. In other cases, limpid and stable compositions were not obtained even with relatively low contents of lead, of the order of 5% by weight.

Examples 29, 32 and 35 show the special properties of the salt of C oxo acid and the triisopropanolamine, which has higher efficiency than that of the triisopropanolamine salts of the other synthetic acids.

TABLE II Lead content of the additive (percent by weight) Miscibility with SAE 90 oil 40 Non-homogeneous mixtures, unstable.

Miscible.

41. 8 Non-homogeneous mixtures, unstable.

34. 7 Limpid concentrates but slight salting- 34 Miseible.

35. 9 Non-homogeneous mixture, unstable.

31, 2 Limpid concentrates but slight salting- 30 Miscible.

1 1 EXAMPLE 36 Mixtures containing respectively 50 parts and 30 parts by weight of each additive of Examples 27-30 and 33, and 50 parts and 70 parts of SAE 90 oil were prepared by heating with agitation at a temperature of 80-90" C. After cooling to ambient temperature, turbid, heterogeneous mixtures were obtained.

The addition at about 50 C. of 4 parts by weight of the triisopropanolamine salt of C oxo acid to the mixtures containing 30 parts of additives, and of 9 parts of the same salt to mixtures containing 50 parts of additives led to compositions which remained limpid and stable after cooling and storage at ambient temperature.

What we claim is:

1. A fluid, stable, homogeneous and limpid additive consisting essentially of a mixture of salts formed by reacting at least one branched chain aliphatic monocarboxylic acid having 5-20 carbon atoms with (a) a basic metallic compound selected from the group consisting of oxides and hydroxides of alkali metals, alkaline earth metals and lead and,

(b) at least one alkanolamine in a mineral oil or synthetic oil.

2. A lubricant additive as claimed in claim 1 wherein the carboxylic acid is prepared by a Koch synthesis.

3. A lubricant additive as claimed in claim 1 wherein the carboxylic acid is prepared by oxo synthesis.

4. A lubricant additive as claimed in claim 3 wherein the carboxylic acid has a chain length in the range C C 5. A lubricant additive as claimed in claim 4 wherein the carboxylic acid is an oxo acid containing 10 carbon atoms.

6. A lubricant additive of claim 1 wherein the molar ratio of the alkanolamine to the basic metallic compound lies in the range 0.1-0.521.

7. A lubricant additive as claimed in claim 6 wherein, when the alkaline earth metal is selected from the group consisting of calcium and barium, the molar ratio of alkanolamine to the basic metallic compound lies in the range 0.1O.3:1.

8. A fluid, stable, homogeneous and limpid lubricant additive having a high metal content consisting essentially of a mixture of salts formed by reacting at least one branched chain aliphatic monocarboxylic acid of chain length C C forming a component of a mixture containing at least one straight chain aliphatic monocarboxylic acid with (a) a basic metallic compound selected from the group consisting of oxides and hydroxides of alkali metals, alkaline earth metals and lead and,

(b) at least one alkanolamine in a mineral oil or a synthetic oil.

9. A lubricant additive as claimed in claim 8 in which the carboxylic acid is a mixture of natural straight chain C-,C aliphatic carboxylic acids and C -C oxo acids and in which the molar ratio of x0 acids to natural acids is greater than 0.1 1.

10. A lubricant additive as claimed in claim 9 wherein when the metallic constituent is calcium, the molar ratio of alkanolamine to calcium is in the range 0.3-0.5:1.

11. A fluid, stable, homogeneous and limpid lubricant additive having a high metal content consisting essentially of a mixture of salts formed by reacting at least one branched chain aliphatic monocarboxylic acid containing 2O carbon atoms with (a) a basic metallic compound selected from the group consisting of oxides and hydroxides of alkali metals, alkaline earth metals and lead and,

(b) a compound selected from the group consisting of triisopropanolamine and mixtures of mono-, diand triisopropanolamine in which triisopropanolamine is the major ingredient in a mineral oil or a synthetic oil.

12. A fluid, stable, homogeneous and limpid lubricant additive having a high metal content consisting essentially of a mixture of salts formed by reacting at least one branched chain aliphatic monocarboxylic acid containing 5-20 carbon atoms with (a) a basic lead compound and (b) triethanolamine the molar ratio of triethanolamine to basic lead compound being 0.3:1 in a mineral oil or a synthetic oil.

13. A fluid, stable, homogeneous and limpid lubricant additive having a high metal content consisting essentially of a mixture of salts formed by reacting a branched chain aliphatic oxo acid having a chain length of 810 carbon atoms with (a) a basic metallic compound selected from the group consisting of oxides and hydroxides of alkali and alkaline earth metals and (-b) a compound selected from the group consisting of mono-, diand triisopropanolamine and mixture thereof in which the triisopropanolamine is the major constituent the ratio of isopropanolamine to basic metallic compound being in the range 0.1-0.3:1 and the mixture of salts being contained in a mineral oil diluent.

14. A lubricant additive as claimed in claim 13 in which the basic metallic compound is calcium and the concentration of mixed salts in the diluent is such as to give a calcium concentration therein of 5-6% by weight.

15. A fluid, stable, homogeneous and limpid lubricant additive having a high metal content consisting essentially of a mixture of salts formed by reacting at least one branched aliphatic monocarboxylic acid selected from the group consisting of C C oxo acids, ethyl hexanoic acid and acid prepared by the Koch synthesis with (a) lead oxide and (b) an alkanolamine selected from the group consisting of diand triisopropanolamine the molar ratio of alkanolamine to lead oxide being 0.3 :1 and the reaction being carried out in a mineral oil diluent to give a stable clear product having a lead concentration in the range 20-40% by weight.

16. A process for the preparation of additives for lubricants comprising neutralising, With at least One branched aliphatic monocarboxylic acid containing 5 to 20 carbon atoms and selected from the group consisting of natural and synthetic branched aliphatic monocarboxylic acids and mixtures thereof with straight chain aliphatic monocarboxylic acids, a basic metallic compound selected from the group consisting of oxides and hydroxides of lead, alkali metals, and alkaline earth metals, said basic metallic compound being intimately mixed with at least one alkanolamine.

17. A process according to claim 16, in which pulverised lead oxide is formed into a paste with the at least one alkanolamine until a homogeneous cream is obtained, an amount of oil corresponding to the desired lead content is then added, after which the acid is progressively introduced, the temperature being maintained at approximately 105 C. until the lead oxide disappears and then being brought to l10-115 C, in order to complete the reaction.

18. A process as claimed in claim 16 in which the basic metallic compound is first mixed with the salt of the amino alcohol and an amount of branched carboxylic acid insufficient to completely react therewith and then the premix thus obtained is completely neutralised with the branched chain carboxylic acid.

19. A process according to claim 18, in which a basic metallic compound selected from the group consisting of alkali metal and alkaline earth oxides and hydroxides in a finely ground state is formed into a paste with the at least one alkanolamine until a homogeneous cream is obtained, the temperature adjusted to 70 C. and an amount of minearl oil corresponding to the desired metallic component content is then added, after which, the amount of acid necessary for neutralisation of all the alkalinity is progressively introduced, during a period of 45-60 minutes during which the temperature is allowed to rise to 7580 C. and the reaction mixture is held at this temperature for at least 60 minutes to complete the reaction.

20. A process for the preparation of an additive for a lubricant comprising forming a paste of pulverised lead oxide with triisopropanolamine to give a homogeneous cream, adding an amount of diluent mineral oil corresponding to the lead contentdesired in the finished product, adding a C oxo acid progressively and maintaining the reaction temperature at approximately 105 C. until the lead oxide disappears and finally raising the reaction temperature to 110-115 C. to complete the reaction,

References Cited UNITED STATES PATENTS Fraser 25242.1 Morway 25240.7 Fucinari et a1. 25234 White et al. 25234X FOREIGN PATENTS 5/1966 Great Britain 252-49.3

US. Cl. X.R. 

